All connectors have some form of latch or hook that performs the actual joining together of parts. The latch usually has some form of back up structure to hold it in place but the most critical part of a connector is usually the latch. The hook part of the latch is generally the most highly stressed part, particularly the fillet radius between the hook face and the body of the latch. These stresses are always tensile stresses and for good fatigue characteristics these need to be kept as low as possible. Past practice has been to keep the fillet radius as large as possible or to have more complex fillet profiles to reduce the stress concentration in this area.